Fuel reformers can be used to convert alcohol fuels into gaseous fuels (reformates) to fuel an engine. For example, an ethanol reformer can reform ethanol into a reformate gas comprising hydrogen (H2), carbon monoxide (CO), and methane (CH4) for combustion in an engine.
The inventors herein have recognized that the amount of reformate gas injected into an engine may be based on an assumption that the fuel reformer is operating efficiently, e.g., that the reformer reforms a substantial fraction of the fuel into reformate. If the reformer is not operating efficiently, a significant amount of non-reformed fuel may be output by the reformer. Gaseous fuel reformate may be injected volumetrically into the engine, thus fuel metering errors may result when the reformer is not operating efficiently. Additionally, if the fuel reformer outputs a significant amount of non-reformed fuel, one or more components of the reformer may be degraded and/or unexpected engine knock may occur.
In one example approach, in order to at least partially address the above issues, a method for monitoring a fuel reformer which reforms ethanol into a reformate gas comprising H2, CO, and CH4 for fueling an engine, is provided. The method comprises: injecting an amount of fuel including an amount of ethanol to be reformed into the fuel reformer; and indicating degradation of the fuel reformer based on the amount of ethanol injected into the fuel reformer and an amount of at least one of H2, CO, and CH4 produced by the fuel reformer. In some examples, mitigating actions may be performed if degradation of the fuel reformer is indicated or unexpected engine knock occurs.
In this way, errors in metering of reformate delivery may be reduced and degradation of various reformer system components may be diagnosed and mitigated. Additionally, engine knock may be reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.